PathPilot robot

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22 Dec 2020 13:20 #192809 by Alpiniste
PathPilot robot was created by Alpiniste
Tormach is unveiling a new robot arm based on ROS+Machinekit:


Youtube

I would love to have pre-made package for robot retrofitting. Is it true that Tormach pushes everything back to open source?
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22 Dec 2020 14:43 - 22 Dec 2020 14:50 #192818 by Aciera
Replied by Aciera on topic PathPilot robot
Using ROS is one possibility to use Linuxcnc with robots. ROS does all the kinematics, simulation and visualization and then sends the joint commands to linuxcnc. Linuxcnc IS already capable of handling most of what is needed for basic handling of robotic arms but compared to commercial controllers' capabilities it's a _lot_ more limited than say even a 5 axis milling machine. Basically all the innovation is in the math hidden inside the controllers.
I don't see a lot of development going on in LinuxCNC when it comes to robot manipulators. One important step was the switch-kins branch but that was not accepted to merge into the master branch so you have to build your own. Unless there is a mechanism to switch between joint and cartesian kinematics in gcode it's fairly pointless to use linuxcnc with a serial manipulator. But, as machinekit, has shown using ROS to do the math is one way to do it.
[edit]
One reason that robot development is not really pursued here is that the manipulators themselves are expensive even without the controllers and the fact that they are not really all that useful for a hobbyist or small shop owner. Those things are built for _very_ repetitive tasks and having a CNC lathe or mill or plasma router will get you a _lot_ more return for the investment than a robot.

And yes I have TWO of them.
To play with. :)
Last edit: 22 Dec 2020 14:50 by Aciera.
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22 Dec 2020 15:33 #192820 by tommylight
Replied by tommylight on topic PathPilot robot
Nice, both of you.
Thanks.

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22 Dec 2020 15:48 #192825 by Alpiniste
Replied by Alpiniste on topic PathPilot robot
I have experience with ROS, I have no experience with LinuxCNC or Tormach's Machinekit version. I would love to have a path for retrofitting older robot arms with broken controllers. I don't understand how ROS clicks into LinuxCNC. LinuxCNC's homepage says that it is a controller for CNC applications. Industrial manipulators and CNC mills are very different beasts used for different tasks. The trajectory planner in ROS is MoveIt and there are many problems with it with many universities and companies working on solving these problems. Honestly I can't see how CNC trajectory planner clicks into this without seriously sucking.

Using vanilla python for programming the robot arm could be huge. If you could use all Python libraries from pip. Integrating tensorflow directly from operator console has great potential. Programming ROS nodes is not easy, this looks easy.
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22 Dec 2020 17:05 - 22 Dec 2020 17:08 #192837 by Aciera
Replied by Aciera on topic PathPilot robot
There are drivers to connect ROS to various Robot controllers. There is one that connects ROS to my working mitsubishi RV-3SDB and I can drive that from moveit just fine.
How exactly machinekit has plugged ROS and Linuxcnc together I don't know but really all you have to do is communicate the joint positions to LinuxCNC and possibly send the encoder positions back to ROS.

Industrial manipulators and CNC mills are very different beasts

_Very_ true and a fact that many people don't realize, including me, until they get a chance to actually work or play with one. Just the fact that the kinematic itself comes with major stumbling blocks like singular points where the inverse kinematics math just folds is a very novel thing to have to work with.

user Grotius is using the KDL library to build a application that plugs into Linuxcnc.
forum.linuxcnc.org/38-general-linuxcnc-q...-c-c?start=80#191018

So since you have experience with ROS, can ROS or the Kinematic libraries do Tool Coordinate Moves?
forum.linuxcnc.org/10-advanced-configura...ics-to-robots#159066
Last edit: 22 Dec 2020 17:08 by Aciera. Reason: add link

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25 Dec 2020 20:10 - 25 Dec 2020 20:11 #193189 by Alpiniste
Replied by Alpiniste on topic PathPilot robot

There are drivers to connect ROS to various Robot controllers.

People are using Arduinos to connect small tabletop robots to ROS ecosystem. This is using Ethercat. You can buy servo with ethercat from China for 500 dollars. Big brand robot controllers are whole package and expensive. I don't think company spending all the dough on state of the art Kuka or ABB will want ROS.

How exactly machinekit has plugged ROS and Linuxcnc together I don't know but really all you have to do is communicate the joint positions to LinuxCNC and possibly send the encoder positions back to ROS.

Above my pay grade. Machinekit is wrapper around Linuxcnc?

So since you have experience with ROS, can ROS or the Kinematic libraries do Tool Coordinate Moves?


ROS path planning works differently to LinuxCNC path planning. You don't have a realtime motion control but buffer full of points in space and time. And you have more than one path planning algorithms at your disposal. You can create as many points as you wish but you don't have folly analytical path description.
Last edit: 25 Dec 2020 20:11 by Alpiniste.

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26 Dec 2020 04:48 #193209 by cmorley
Replied by cmorley on topic PathPilot robot

Tormach is unveiling a new robot arm based on ROS+Machinekit:


I would love to have pre-made package for robot retrofitting. Is it true that Tormach pushes everything back to open source?


The look ahead trajectory planner was pushed back to linuxcnc.
fanuc subroutines are probably from Tormach.

We surely haven't incorporated everything they offer - there is no official process.
And the longer we are forked the harder it is to incorporate code.

If they are using Machinekit then that pretty much ends what we can use (IMHO)

i had voiced the opinion that we should have considered using their HAL code, but that was not popular among the few developers we have.


Linuxcnc can run robots directly but not in anyway you would usually run them for industry and it's not a focus of any real development.
Interfacing to ROS was a smart solution.
I would bet that someone could write code to connect our HAL to ROS.
But i still think it would be smarter to get out motion controller use their HAL code.

I think running real robots (indirectly) with linuxcnc is an exciting development - congrats to Machinekit and Tormach!

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26 Dec 2020 12:47 #193226 by tommylight
Replied by tommylight on topic PathPilot robot
Side info:
Having worked with industrial Kuka robots, the amount of parameters and settings and constraints and interlocks implemented is astonishing.
So being able to control such machine with LinuxCNC with a week or two of effort is also astonishing, and is a testament to the flexibility of LinuxCNC.
Of course it does not have everything the industrial ones have, but industrial ones do not have everything sorted out either, check "singularity" as it is still an issue with them.

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29 Dec 2020 13:03 - 29 Dec 2020 13:03 #193417 by thefabricator03
Replied by thefabricator03 on topic PathPilot robot

I would bet that someone could write code to connect our HAL to ROS.


I think someone already has, github.com/tomlarkworthy/linuxCNC_ROS
Last edit: 29 Dec 2020 13:03 by thefabricator03.

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